diff --git a/LetsEncrypt-SiteExtension/Models/AuthenticationModel.cs b/LetsEncrypt-SiteExtension/Models/AuthenticationModel.cs
index 9507862..230a641 100644
--- a/LetsEncrypt-SiteExtension/Models/AuthenticationModel.cs
+++ b/LetsEncrypt-SiteExtension/Models/AuthenticationModel.cs
@@ -101,7 +101,8 @@ public static explicit operator AuthenticationModel(AppSettingsAuthConfig config
                 AuthenticationEndpoint = config.AuthenticationEndpoint,
                 AzureWebSitesDefaultDomainName = config.AzureWebSitesDefaultDomainName,
                 ManagementEndpoint = config.ManagementEndpoint,
-                TokenAudience = config.TokenAudience
+                TokenAudience = config.TokenAudience,
+                SiteSlotName = config.SiteSlotName
             };
         }
     }
diff --git a/LetsEncrypt.SiteExtension.Core/ArmHelper.cs b/LetsEncrypt.SiteExtension.Core/ArmHelper.cs
index 9ee6480..5776ae0 100644
--- a/LetsEncrypt.SiteExtension.Core/ArmHelper.cs
+++ b/LetsEncrypt.SiteExtension.Core/ArmHelper.cs
@@ -1,5 +1,4 @@
 using LetsEncrypt.SiteExtension.Models;
-using Microsoft.Azure.Management.Resources;
 using Microsoft.Azure.Management.WebSites;
 using Microsoft.IdentityModel.Clients.ActiveDirectory;
 using Microsoft.Rest;
diff --git a/LetsEncrypt.SiteExtension.Core/KuduHelper.cs b/LetsEncrypt.SiteExtension.Core/KuduHelper.cs
index d120e3d..9fbc0dd 100644
--- a/LetsEncrypt.SiteExtension.Core/KuduHelper.cs
+++ b/LetsEncrypt.SiteExtension.Core/KuduHelper.cs
@@ -14,7 +14,7 @@ public static KuduRestClient GetKuduClient(this WebSiteManagementClient client,
         {
             var user = client.WebApps.GetPublsihingCredentialSiteOrSlot(settings.ResourceGroupName, settings.WebAppName, settings.SiteSlotName);
 
-            return new KuduRestClient(settings, settings.WebAppName, user.PublishingUserName, user.PublishingPassword);
+            return new KuduRestClient(settings, user.PublishingUserName, user.PublishingPassword);
         }
     }
 }
diff --git a/LetsEncrypt.SiteExtension.Core/KuduRestClient.cs b/LetsEncrypt.SiteExtension.Core/KuduRestClient.cs
index 3288c5c..cd79fd3 100644
--- a/LetsEncrypt.SiteExtension.Core/KuduRestClient.cs
+++ b/LetsEncrypt.SiteExtension.Core/KuduRestClient.cs
@@ -16,9 +16,9 @@ public class KuduRestClient
         private string publishingUserName;
         private string webAppName;
 
-        public KuduRestClient(IAzureEnvironment azureEnvironment, string webAppName, string publishingUserName, string publishingPassword)
+        public KuduRestClient(IAzureEnvironment azureEnvironment, string publishingUserName, string publishingPassword)
         {
-            this.webAppName = webAppName;
+            this.webAppName = string.IsNullOrEmpty(azureEnvironment.SiteSlotName) ? azureEnvironment.WebAppName : azureEnvironment.WebAppName + "-" + azureEnvironment.SiteSlotName;
             this.publishingUserName = publishingUserName;
             this.publishingPassword = publishingPassword;
             this.baseUri = $"https://{this.webAppName}.scm.{azureEnvironment.AzureWebSitesDefaultDomainName}";
diff --git a/LetsEncrypt.SiteExtension.WebJob/Functions.cs b/LetsEncrypt.SiteExtension.WebJob/Functions.cs
index d49bfd8..52fa45c 100644
--- a/LetsEncrypt.SiteExtension.WebJob/Functions.cs
+++ b/LetsEncrypt.SiteExtension.WebJob/Functions.cs
@@ -39,11 +39,13 @@ public class Functions
         public static void AddCertificate([TimerTrigger(typeof(MonthlySchedule), RunOnStartup = true)] TimerInfo timerInfo, [Blob("letsencrypt/firstrun.job")] string input, [Blob("letsencrypt/firstrun.job")] out string output)
         {
             Console.WriteLine("Starting add certificate");
-            string websiteName = Environment.GetEnvironmentVariable("WEBSITE_SITE_NAME");
+            var environment = new Models.AppSettingsAuthConfig();
+            string websiteName = environment.WebAppName + "-" + environment.SiteSlotName + "|";
             if (string.IsNullOrEmpty(input) || !input.Contains(websiteName))
             {
-                new CertificateManager(new Models.AppSettingsAuthConfig()).AddCertificate();
-                output = string.IsNullOrEmpty(input) ? websiteName : input + '|' + websiteName;
+                Console.WriteLine($"First run of add certificate for {websiteName}");
+                new CertificateManager(environment).AddCertificate();
+                output = string.IsNullOrEmpty(input) ? websiteName : input + websiteName;
             }
             else
             {
diff --git a/LetsEncrypt.SiteExtension.WebJob/Program.cs b/LetsEncrypt.SiteExtension.WebJob/Program.cs
index 0438fb3..ee3d8c3 100644
--- a/LetsEncrypt.SiteExtension.WebJob/Program.cs
+++ b/LetsEncrypt.SiteExtension.WebJob/Program.cs
@@ -19,7 +19,8 @@ static void Main()
             config.UseTimers();
             //A host ID must be between 1 and 32 characters, contain only lowercase letters, numbers, and 
             //dashes, not start or end with a dash, and not contain consecutive dashes.
-            var hostId = "letsencrypt-" + Environment.GetEnvironmentVariable("WEBSITE_SITE_NAME");            
+            var environment = new Models.AppSettingsAuthConfig();
+            var hostId = "le-" + environment.WebAppName + environment.SiteSlotName;
             config.HostId = hostId.Substring(0,hostId.Length > 32 ? 32 : hostId.Length).TrimEnd(new[] { '-' }).ToLower();
 
             var host = new JobHost(config);
diff --git a/LetsEncrypt.nuspec b/LetsEncrypt.nuspec
index 5ce0db4..cb896fb 100644
--- a/LetsEncrypt.nuspec
+++ b/LetsEncrypt.nuspec
@@ -3,7 +3,7 @@
   <metadata>
     <id>letsencrypt</id>
     <title>Azure Let's Encrypt (x86)</title>
-    <version>0.6.14</version>
+    <version>0.6.16</version>
     <authors>SJKP</authors>
     <licenseUrl>http://opensource.org/licenses/Apache-2.0</licenseUrl>
     <projectUrl>https://github.com/sjkp/letsencrypt-siteextension</projectUrl>
diff --git a/LetsEncrypt64.nuspec b/LetsEncrypt64.nuspec
index 24c55e8..7cbad6c 100644
--- a/LetsEncrypt64.nuspec
+++ b/LetsEncrypt64.nuspec
@@ -3,7 +3,7 @@
   <metadata>
     <id>letsencrypt64</id>
     <title>Azure Let's Encrypt (x64)</title>
-    <version>0.6.14</version>
+    <version>0.6.16</version>
     <authors>SJKP</authors>
     <licenseUrl>http://opensource.org/licenses/Apache-2.0</licenseUrl>
     <projectUrl>https://github.com/sjkp/letsencrypt-siteextension</projectUrl>